Liquid removal system which is compressible in the longitudinal and/or in the transverse direction

ABSTRACT

The present invention provides a liquid removal system for applications where there is a need for liquid removal including laboratories and workshops as well as medical applications as well as dental applications. The liquid removal system exhibits improved wearing comfort by comprising an interface device which is compressible in the longitudinal and/or transverse dimension.

FIELD OF THE INVENTION

The present invention provides a liquid removal system for applicationswhere there is a need for liquid removal including laboratories andworkshops as well as medical applications as well as dentalapplications.

BACKGROUND

Articles to manage body exudates such as urine are well known in theart. In this context, managing body exudates includes acquiring,distributing, and storing body exudates such as urine, menses fecalmaterial, and the like. A wide variety of article has been proposedincluding diapers, sanitary napkins, adult incontinence articles such asbriefs or bed mats, underarm sweat pants, catheters, bottles, bed pans,and the like.

In U.S. Pat. No. 5,678,564 (Lawrence et al.) and U.S. Pat. No. 5,911,222(Lawrence et al.) a liquid removal system having an interface device anda vacuum source is described. The interface device has a porous membranewith an entrance zone on one side. The vacuum source maintains a vacuumon the side of the membrane opposite the entrance zone when the membraneis wetted. Liquid which contacts the wetted porous membrane is removedfrom the interface device by the vacuum source. Whilst this device iscapable of acquiring and transporting urine, this liquid removal systemcomprises a plastic shell which is only capable to conform to minordifferences in the physique of a patient. In particular for mobilepatients, it is however desirable to provide a liquid removal systemwhich readily adapts to the movements of the patient by beingcompressible in the longitudinal and/or in the transverse direction.

Hence, it is an object the present invention to overcome the problemsposed by the liquid removal systems of the prior art.

It is a further object of the present invention to provide a liquidremoval system which is compressible in the longitudinal and/or in thetransverse direction.

SUMMARY OF THE INVENTION

The liquid removal system of the present invention comprises aninterface device. The interface device is intended to acquire the bodyliquid from the wearer and accordingly is intended to be worn close tothe urethra exit of the wearer. The interface device comprises a firstzone, a second zone, and a porous membrane separating the first zonefrom the second zone. The second zone is adapted to be connected to asuction source and a porous membrane is capable of maintaining a suctionin the second zone without permitting air from the first zone to passthrough the membrane into the second zone when the membrane has beenwetted with a first liquid. A second liquid is removed from the firstzone by the suction in the second zone upon entering the first zone andcontacting the porous membrane by passing through the membrane into thesecond zone. The first zone of the liquid removal system of the presentinvention has the user facing surface and the second zone has a backsurface. The liquid removal system of the present invention ischaracterized in that its interface device is compressible in thelongitudinal direction and/or is compressible in the transversedirection.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a plan view of the absorbent article of the presentinvention.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a liquid removal system of the present invention. Thesystem comprises a first zone 25, a second zone 35, a user facingsurface 21 of the first zone, a garment facing surface 26, and a porousmembrane 33.

DETAILED DESCRIPTION OF THE INVENTION

Materials suitable for the membrane of the present invention and suctionsources suitable for the liquid removal system of the present inventionare described for example in U.S. Pat. No. 5,678,564 (Lawrence et al.)U.S. Pat. No. 5,911,222 (Lawrence et al.) incorporated herein byreference. Preferably, the membrane material can be bend to an extentwhich includes most of the typical in-use conditions withoutsubstantially loosing its functionality. More preferably, the membranematerial of the present invention has a low bending moment along atleast one of the two major axis of its major surfaces in order toimprove the comfort of the system. Preferably, the suction source as awhole or at least those parts connecting the suction source with thesecond zone of the liquid removal system are chosen to be flexibleand/or compressible in order to improve the comfort of the system.

For the purpose of the present invention, a locally Cartesian coordinatesystem is defined relative to the liquid removal system and itspositioning relative to the wearer during use. The longitudinal orx--direction is defined as the direction running from the front waistregion of the wearer to the back waist region of the web. Typically, thelongitudinal direction is the longest dimension of the liquid removalsystem. The transverse or y--direction is defined as direction runningfrom the left side of the wearer to the right side of the wearer. Thez--direction is normal to the x--direction and to the y--direction andaccordingly is also substantially normal to the body surface of thewearer during use. It is to be understood in this context that duringwear of the liquid removal system of the present invention the liquidremoval system conforms to the body shape of the wearer and thataccordingly the coordinate axis at the front region of the liquidremoval system may not coincide with the coordinate axis in the backregion of the liquid removal system.

The liquid removal system of the present invention is compressibleeither in the longitudinal direction or in the transverse direction. Itmay also be compressible in longitudinal direction as well as in thetransverse direction. The term “compressible” as used herein refers toliquid removal systems which change their longitudinal and/or transversedimension as a result of a relatively low external pressure or forceexerted onto liquid removal system in that direction. Thiscompressibility leads to increased comfort during wear of the liquidremoval system since the compressibility of the liquid removal systemallows the liquid removal system to adapt to the changing body shape ofthe wearer. Substantial changes of the body shape of the wearer arepresent for mobile patients as well as for bed ridden patients.Preferably, the liquid removal system of the present invention iscompressible in the respective direction to less than 90 percent of itsoriginal dimension in that direction under a compressive pressure of 10kPa, more preferably to less than 80 percent of its original dimensionin that direction, most preferably to less than 60 percent of itsoriginal dimension in that direction.

The user facing surface of the first zone of the liquid removal systemof the present invention is intended to be worn adjacent to the bodysurface of the wearer in proximity to the urethra exit. The user facingsurface comprises a urine acquisition zone which may coincide with thesurface dimensions of the total user facing surface of the liquidremoval system or which may be covering only a portion of the userfacing surface. At least the urine acquisition zone of the user facingsurface may be covered by soft, hydrophobic topsheet. For improvedcomfort, the topsheet material may be chosen to have a low bendingmoment in the longitudinal and/or transverse direction. Materialssuitable for the topsheet of the present invention include but are notlimited to woven and nonwoven materials comprising natural fibers,synthetic fibers, or combinations thereof. A preferred to topsheetmaterial is a carded nonwoven web material. More preferably, the cardednonwoven web material comprises crimped staple fibers. Furthermore, thetopsheet material may be a high bulk nonwoven web material.

The second zone may comprise a flexible support means and may beenveloped by a flexible, liquid impermeable material. A wide variety offlexible support means are known in the art such as for example opencell, polymeric foams or framework structures made from syntheticpolymeric material. Additionally, a wide variety of suitable liquidimpermeable materials is known in the art such as for example films ofpolymeric material, nonwoven web material, and the like. For improvedcomfort, the backsheet material may be chosen to have a low bendingmoment in the longitudinal and/or transverse direction. Further, thebacksheet material may be covered by a fibrous, for example nonwoven,material to improve the tactile feel of its outer surface. The flexiblesupport means may be compressible in the longitudinal and/or in thetransverse direction. Preferably, the flexible support means iscompressible in the longitudinal and/or transverse direction to lessthan 90 percent of its original dimension in that direction, morepreferably to less than 80 percent of its original dimension thatdirection, most preferably to less than 60 percent of its originaldimension in that direction under a compressive pressure of 10 kPa. Theflexible support means of the present invention may comprise a pluralityof substantially incompressible elements. It is to be understood in thiscontext that these substantially incompressible elements must not fillup all a void volume inside the second zone of the liquid removal systemin order to allow the second liquid to be transported away from themembrane. For example, the substantially incompressible elements may bespheres, Raschig rings, Pearl saddles. At least a portion of thesubstantially incompressible element may be free movable inside thesecond zone in order to improve compress ability while still maintainingthe overall volume of the second zone.

The user facing surface of the liquid removal system may comprise anexternal dam to see of the device to the wearer thereby preventingleakage of urine. The external dam may comprise a liquid impermeablenonwoven barrier cuff such as those well known from disposable absorbentarticles. Such a barrier cuff may comprise elastification means in orderto improve conformity with the body of the wearer during use.Preferably, the barrier cuff of the present invention is vapor permeableto improve the breathability of the liquid removal system.

The liquid removal system of the present invention may comprise analignment means which aligns the urine acquisition zone with the exit ofthe urethra of the wearer. The alignment means may comprise a memberdisposed onto the user facing surface which is shaped according to thebody surface of the wearer in order to impede excessive movement of theliquid removal system relative to the body of the wearer during use. Inparticular for male patients, the alignment means may align the urineacquisition zone with the distal end of the penis of the wearer such asby mechanical means limiting the movement of the penis relative to theurine acquisition zone.

As is readily apparent to the skilled person, the comfort improvementscan only be achieved by providing a liquid removal system exhibiting asufficient performance for example in terms of acquisition rate, liquidtransportation rate, storage capacity, membrane performance, and thelike.

In the following, a suitable embodiment of the liquid removal system andof suitable members for a liquid removal system respectively will bedescribed. The liquid removal system is assembled from an open celledfoam material which is completely enveloped by a membrane. A suitablemembrane material is available from SEFAR of Rüschlikon, Switzerland,under the designation SEFAR 03-20/14. A suitable foam material isavailable from Recticel of Brussels, Belgium, under the designationBulpren S10 black. A suitable technique to completely envelope the foammaterial with the membrane material is to wrap the membrane materialaround the foam material and to subsequently heat seal all open edges ofthe membrane material. It will be readily apparent to the skilledpractitioner to choose other similarly suitable materials. Depending onthe specific intended application of the liquid removal system, it mayalso be required to choose similar materials with slightly differentproperties. After assembly, the liquid removal system is activated byimmersing the liquid removal system in water or in synthetic urine untilthe liquid removal system is completely filled with liquid and until themembranes are completely wetted with liquid. After activation, a part ofthe liquid inside the liquid removal system may be squeezed out byapplying an external pressure to the liquid removal system. If theactivation of the liquid removal system was successful, the liquidremoval system will not suck air through the membranes.

The particular geometry of the liquid removal system of the presentinvention can be varied to according to the specific requirements offthe intended application. If, for example, the liquid removal system isintended to be used in an absorbent article the liquid removal systemmay be defined such that its zone of intended liquid acquisition fitsbetween the legs of the wearer and further that its intended liquiddischarge zone matches the form of the storage member associated to it.Accordingly, the outer dimensions of the liquid removal system such aslength, width, or thickness may also be adapted to the specific needs ofthe intended application. In this context, it has to be understood,however, that the design of the outer form of the liquid removal systemmay have an impact on its performance. For example, certain crosssections of the liquid removal system directly impact on its flow rate.

For application of the liquid removal system in an absorbent articleaccording to the present invention, the liquid removal system iscombined with a storage member. The term “liquid storage member” refersto a member which is capable of receiving and storing liquid. The volumeof the liquid storage member may vary with the amount of stored liquidsuch as by swelling. Typically, the storage member will imbibe theliquid by means of capillary suction and/or osmotic pressure. Otherstorage members may also use vacuum as a means to store the liquid. Theliquid storage member is further capable of holding at least a portionof the stored liquid under external compressive pressure. Suitablestorage members are well known in the art and may comprise for example asuper absorbent polymeric material such as polyacrylate. The storagemember may further comprise a fibrous structure, such as a pad ofcellulosic fibers, in which the particulate superabsorbent material isdispersed. In order to pick up the liquid discharged from the liquidremoval system, the storage member may be placed in direct liquidcommunication with the intended liquid discharge zone of the liquidremoval system. A suitable storage member is for example asuperabsorbent polymer such as available from CHEMDAL, United Kingdom,under the designation ASAP400.

Further examples of suitable superabsorbent polymers, often alsoreferred to as “hydrogel forming polymer” or “absorbent gellingmaterial”, are described in U.S. Pat. No. 5,562,646 (Goldman et al.),issued Oct. 8, 1996 and U.S. Pat. No., 5,599,335 (Goldman et al.),issued Feb. 4, 1997.

Other liquid removal systems suitable for the purposes of the presentinvention are described for example in the PCT patent application No.PCT/US98/13497 entitled “Liquid transport member for high flux ratesbetween two port regions” filed in the name of Ehrnsperger et al. filedon Jun. 29, 1998, and in the following PCT patent applicationsPCT/US99/14796 entitled “High flux liquid transport members comprisingtwo different permeability regions” (P&G case CM1840MQ) filed in thename of Ehrnsperger et al., PCT/US99/14654 entitled “Liquid transportmember for high flux rates between two port regions” (P&G case CM1841MQ)filed in the name of Ehrnsperger et al., PCT/US99/14638 entitled “Liquidtransport member for high flux rates against gravity” (P&G caseCM1842MQ) filed in the name of Ehrnsperger et al., PCT/US99/14633entitled “Liquid transport member having high permeability bulk regionsand high bubble point pressure port regions” (P&G case CM1843MQ) filedin the name of Ehrnsperger et al. All of these documents are enclosedherein by reference.

In one embodiment of the present invention, the liquid removal system ofthe present invention is geometrically saturated or substantiallygeometrically saturated with free liquid. The term “free liquid” as usedherein refers to liquid which is not bound to a specific surface orother entity. Free liquid can be distinguished from bound liquid bymeasuring the proton spin relaxation time T2 of the liquid molecules aaccording to NMR (nuclear magnetic resonance) spectroscopy methods wellknown in the art.

The term “geometrically saturated” as used herein refers to a region ofa porous material in which the liquid accessible void spaces have beenfilled with a liquid. The void spaces referred to in this definition arethose which are present in the current geometric configuration of theporous material. In other words, a geometrically saturated device maystill be able to accept additional liquid by and only by changing itsgeometric configuration for example by swelling, although all voids ofthe device are filled with liquid in the current geometricconfiguration. A device for handling liquids is called geometricallysaturated, if all porous materials that are part of the device andintended for liquid handling are geometrically saturated.

The term “porous material” as used herein refers to materials thatcomprise at least two phases a solid material and a gas or voidphase—and optionally a third liquid phase that may be partially orcompletely filling said void spaces. The porosity of a material isdefined as the ratio between the void volume and the total volume of thematerial, measured when the material is not filled with liquid.Non-limiting examples for porous materials are foams such aspolyurethane, HIPE (see for example PCT patent application WO94/13704),superabsorbent foams and the like, fiber assemblies such as meltblown,spunbond, carded, cellulose webs, fiber beds and the like, porousparticles such as clay, zeolites, and the like, geometrically structuredmaterials such as tubes, balloons, channel structures etc. Porousmaterials might absorb liquids even if they are not hydrophilic. Theporosity of the materials is therefore not linked to their affinity forthe liquid that might be absorbed.

The term “substantially geometrically saturated” as used herein refersto a member in which at least 90% of the macroscopic void volume of themember are geometrically saturated, preferably at least 95% of themacroscopic void volume of the device are geometrically saturated, morepreferably 97% of the macroscopic void volume of the device aregeometrically saturated, most preferably 99% of the macroscopic voidvolume of the device are geometrically saturated.

In one embodiment of the present invention, the absorbent article is adisposable absorbent article such as a diaper, a training pant, asanitary napkin, an adult incontinence article, or the like. Such anabsorbent article may further comprise a liquid pervious topsheet, aliquid impervious backsheet at least partially peripherally joined tothe topsheet. The absorbent article may further comprise an absorbentcore which may serve as a storage member for the urine. Topsheets,backsheet, and absorbent cores suitable for the present invention arewell known in the art. In addition, there are numerous additionalfeatures known in the art which can be used in combination with theabsorbent article of the present invention such as for example closuremechanisms to attach the absorbent article around the lower torso of thewearer.

1. A liquid removal system which comprises an interface device, saidinterface device comprising a first zone and a second zone and having aporous membrane separating said first zone from said second zone, saidsecond zone being adapted to be connected to a suction source, saidporous membrane being capable of maintaining a suction in said secondzone without permitting air from said first zone to pass through saidmembrane into said second zone when said membrane has been wetted with afirst liquid; said suction being maintained until said membrane iscontacted with a second liquid; and wherein said second liquid uponentering said first zone and contacting said porous membrane is removedfrom said first zone by said suction in said second zone by passingthrough said membrane into said second zone said first zone having auser facing surface, said second zone having a back surface,characterized in that said interface device is compressible in thelongitudinal direction and/or is compressible in the transversedirection to less than 90 percent of its original dimension in thatdirection, wherein said second zone comprises a flexible support meansand said second zone is enveloped by a flexible, liquid impermeablebacksheet, wherein said flexible support means comprises a plurality ofsubstantially incompressible elements, at least a portion of saidplurality of substantially incompressible elements being freely movableinside said second zone.
 2. A liquid removal system according to claim1, said user facing surface comprising a urine acquisition zone whereinat least said urine acquisition zone is covered by a soft, complianttopsheet.
 3. A liquid removal system according to claim 2 wherein saidtopsheet is a carded nonwoven web material.
 4. A liquid removal systemaccording to claim 3 wherein said carded nonwoven web material is a highbulk nonwoven web material.
 5. A liquid removal system according toclaim 1 wherein said plurality of substantially incompressible elementscomprises elements selected from the group of spheres, Raschig rings,Pearl saddles.
 6. A liquid removal system according to claim 1 whereinsaid flexible liquid impermeable backsheet comprises a layer of nonwovenweb material on its outer surface.
 7. A liquid removal system accordingclaim 1 wherein said liquid removal system further comprises an externaldam disposed onto the user facing surface of said first zone whereinsaid external dam comprises a liquid impermeable nonwoven barrier cuff.8. A liquid removal system according to claim 7 wherein said nonwovenbarrier cuff is vapor permeable.